This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The AMBER force field has been widely used for simulating nucleic acid polymers (DNA, RNA) employing the parameters developed principally by Dr. Cheatham. Because of the ability of our GLYCAM parameters to accurately model carbohydrate rings, he has asked us to extend our parameters to nucleic acids. This is a major project, but has the potential to overcome some long-standing weaknesses in the AMBER parameters.